Streptococcal pharyngitis is the acute disease that precedes the chronic disease process of rheumatic heart disease (RHD). Recent studies have revealed that the microbiologic and epidemiologic features of RHD in tropical environments are distinct from those described in the literature, which are based mostly on studies from temperate zone communities. Whether these differences are due to temperate versus tropical environment, or the nature of community structures in the so-called tropical areas slum versus non- slum remains unknown. In Brazil, RHD appears to occur predominantly in populations that reside in urban slums (favelas). RHD epidemiology in slums may be very distinct from what is described in the literature. This may be due to structural, social or other aspects of slums. Effective prevention strategies depend on understanding the disease dynamics in a population. Therefore, this project seeks to study the early events that are known to be associated with the eventual outcome of RHD in these communities. Specifically, this project will compare the epidemiology and microbiology of streptococcal pharyngitis in contrasting populations- -slum versus non-slum--in the same urban center. Specific Aims: One aim of the CDC Health Protection Goal of Healthy People in a Healthy World is to prevent infectious diseases and their consequences. This study will help achieve this objective with the following studies: 1.) An assessment of the diversity and clonal composition of Group A Streptococcus isolates from pharyngitis (symptomatic) cases from favela and non-favela populations in the same urban setting in a developing country (Salvador, Brazil), and a comparison of these isolates with the population structure of GAS from an unrelated geographic setting in a developed country (Oakland, CA, USA); and 2.) An evaluation of the relative prevalence, proportion, and clonal composition of Group G Streptococcus (GGS) and Group C Streptococcus (GCS) from pharyngitis (symptomatic) cases in three populations: favela and non-favela populations in Salvador, Brazil; and a pediatric population in Oakland, CA, USA. Research Design and Methods: Streptococcal isolates will be collected from children aged 5-14 who present with pharyngitis to two clinics in Salvador, Brazil. One clinic serves a population with high socioeconomic status, and the other clinic serves a favela population. Isolates will be genotyped and analyzed for clonal diversity and serogroup with emm-typing, as well as multilocus sequence typing (MLST). Conclusion: By addressing these aims, this study will determine whether streptococcal pharyngitis in a slum population has patterns distinct from that described in the medical literature; and also from communities in the same city but which are not considered slums. Past literature has demonstrated that strain type (based on M surface protein) has important implications for development of RHD. It is important that we assess this known risk factor in a slum community at high risk for RHD. [unreadable] [unreadable] [unreadable] [unreadable]